1. Field of the Invention
The present invention relates generally to the field of engines which convert fuel and heat into mechanical energy. More specifically the present invention relates to a thermal engine such as for powering a vehicle, including a cylinder and piston and an insulated thermal battery including at least a thermal mass such as an engine block for storing and retaining heat to enhance or cause fluid expansion within the cylinder and drive the piston, the thermal battery optionally including an electrolyte chamber containing a thermal electrolyte for functioning as an electric thermal battery.
In its most basic form, as mentioned above, generally. The engine uses a modified conventional single or multi-cylinder gas engine configuration with the addition of a thermal mass to store power in the form of heat. The engine incorporates several conventional engine elements including a piston with a piston head and a piston rod or crank, an engine block made up of a cylinder case and a crankcase and containing a tubular cylinder within which the piston head is slidably and sealingly retained, a cylinder head including intake and exhaust valve ports and valves and defining an expansion chamber within the cylinder between the piston head and the cylinder head, a crank shaft mechanically linked to the piston opposite the cylinder head by the piston crank, valve operating means driven by rotation of the drive shaft, an expansion fluid tank, fluid delivery means for delivering expansion fluid from the fluid tank into the chamber, a thermal battery including a thermal mass for storing heat and in thermal communication with the chamber for heating expansion fluid within the chamber, thermal insulation surrounding the thermal battery for efficiently containing heat within the thermal mass for delivery into the chamber, thermal insulation surrounding said expansion fluid tank for efficiently containing heat within said expansion fluid, and engine starting means. The valve operating means preferably includes a cam shaft and push rods riding on cams along the cam shaft which pivot rocker arms in conventional fashion. A flywheel preferably is attached to the crankshaft and centered at the crankshaft rotational axis, and an output shaft coaxial with and fixedly connected to an end of the crankshaft preferably extends out of the crankcase through a shaft port to transmit engine power in the form of torque to any desired mechanical load. The expansion fluid delivery means preferably is a substantially conventional fuel injection system with an electronic controller module.
In general operation of the engine, heat is stored in the thermal battery which may consist solely of a thermal mass capable of storing heat such as by passing electric current through resistance heating elements embedded in the thermal mass, which preferably includes the engine block itself, the engine is started (the crankshaft is rotated), the intake valve is opened, the expansion fluid delivery means delivers a quantity of expansion fluid into the cylinder and then closes, and the heat stored in the fuel and in the thermal battery either causes or assists the expansion fluid to expand within the cylinder, whether by phase change or combustion, pushing the piston from a position at or near top dead center to bottom dead center, thereby rotating the crank shaft and producing mechanical energy. The exhaust valve then opens and continued angular momentum and rotation of the crank shaft and flywheel drives the piston back toward the cylinder head, pushing the remaining elements of the expansion fluid out of the cylinder so that the intake valve can again open and the exhaust valve close and the cycle repeat. The thermal mass is preferably a dense metal allow of high heat retention capacity, so that its coefficient of heat absorption is as high as possible. Iron alloys in combination with steel and titanium may be used as a thermal mass, however, several types of alloys can be used for the same purpose. The thermal mass could also be a shell of metal with very high melting point with a molten metal of lower melting point contained therein, so that the metal could be used to store as much heat as possible.
The engine preferably operates alternately on a combustible expansion fluid such as gasoline or natural gas, and on a noncombustible expansion fluid such as water. To this end, ignition means are provided in communication with the chamber for igniting a combustible fuel within the expansion chamber. A combustible fluid tank and a noncombustible fluid tank are further provided, which are each alternately and respectively in fluid communication with the fuel injection system through a combustible fluid line and fluid pump and a noncombustible fluid line and fluid pump. The non-combustible fluid tank is provided with heating elements for heating the expansion fluid to a temperature close to the boiling point of the expansion fluid. The non-combustible fluid tank is surrounded with an insulating material, to prevent heat loss from the tank. Advantageously, the heated expansion fluid is close to its vaporization temperature, and so little additional heating from the thermal battery can said expansion fluid to expand into a gas and do mechanical work.
In one embodiment of the invention, the Expansion fuel tank may be eliminated completely and replaced with an Expansion Fluid cooling coil so that the Expansion fuel may be recycled continuously to do work.
2. Description of the Prior Art
So-called multi-fuel and hybrid engines are known that can operate with different types of fuels and are based on certain thermodynamic principles, such as the Carnot cycle, the Rankine cycle, the Diesel cycle, or the Otto cycle in conjunction with stored electrical power to drive motors. These engines may also have heating elements for heating the engine block prior to starting the engine from a cold start, but the purpose of heating the engine block is not to reuse the heat from the block, but to preheat the fuel and engine for an easy start.
In combustion engines an air-fuel mixture is compressed and then ignited. The compression results in an expansion of gases within the cylinder chamber, pushing a piston slidably retained within the cylinder in a repeated cycle to turn a crank shaft and so to generate mechanical power from the fuel. The current prior art engines therefore rely only on combustible fuels that cause global pollution and health associated problems. In an effort to reduce the pollution and dependence on fossil fuels, several types of hybrid engines have been invented including electrically powered vehicles which rely on the storage of electric power in batteries in chemical form.
While these vehicles are of current interest, a growing concern about the disposal of electric batteries, and the efficient global transformation of these new technologies to replace existing technologies has emerged.
What is needed is an engine design which adopts a philosophy of replacing or assisting existing technologies such as fossil fuel engines and electric powered engines, and which thermally generates power and improves efficiencies of current designs without substantial change to current engine manufacturing technology.
It is thus an object of the present invention to provide an engine which can be operated with two types of expansion fluids having different means of expansion and thereby achieve a high degree of efficiency during operation. An engine of this kind, in accordance with the invention, uses one of two fuels to operate. Fuels of the combustible type can be used as in conventional technologies to generate power by exploding the fluids within the engine to generate expansive power. Fuels of the non-combustible type, such as water, can be used when such an engine is provided with a new type of thermal energy storage battery technology. As opposed to electrical batteries that store power chemically for later use, a thermal battery of the type used in this invention only stores thermal energy in a thermal mass. Since the energy from such a thermal battery can be substantially used to expand a liquid such as water to a gas, the battery can be used to store enough energy at earlier times, to power an engine that requires low torque at later times. In some cases, the thermal mass of such a battery can be used as an electrolyte to also store energy in both chemical and thermal forms for later uses. The thermal battery can then be optimized by its geometry through maximizing the thermal mass and minimizing the surface area of the thermal battery for storing a maximum amount of thermal energy in the form of a direct heat with little losses. Without limiting the scope of the invention, however, the preferred mode of operation is in a pure thermal mode where the thermal battery is simply a thermal mass for storing heat. The expansion fluid that is used in such a battery can be stored in an insulated tank that allows heating of the expansion fluid to a temperature close to its boiling point. Thus, little additional will be needed to expand the expandible fluid to its gaseous form by a phase change and thus to do work on an engine.
One of the great advantages of such an engine, is that when the engine encounters higher altitudes than the altitudes at which it is charged with heat, its efficiency is higher, since the expansion fluid can expand at even lower temperatures that at such lower altitudes. So the engine can be used in low torque applications at high altitudes.
It is another object of the present invention to provide and thermal battery which can be used in conjunction with a molten electrolyte contained within the battery as a thermal mass to store both heat and electric energy simultaneously.
It is still another object of the present invention to provide such an engine in which pressure generated when vapor expands from a liquid state can then be used when the engine operates as a vapor powered engine, whereof, a liquid such as water or a combination of water and ethanol is injected into the thermal mass of the engine to generate expanded steam when the cylinder head is at top dead-center. Advantageously, much more energy can be stored in such a thermal battery than in a conventional electric battery of the same weight.
It is another objective of this invention to provide such an engine that uses an expansion fluid that is preheated close to its boiling point, so that a thermal mass that stores thermal energy cab be used to store thermal energy which can later be used to expand said expansion fluid to a gas and generate power to drive said engine.
It is an objective of the present invention to disclose a thermal engine which uses a closed cycle to recycle an Expansion fuel.
It is finally an object of the present invention to provide such an engine which is highly efficient and easy to operate.